Tube drawing



Se t. 28, 1937. w. c. WEBER 20,522

TUBE DRAWING Original Filed Dec. 18, 1930 3 .Sheets-Sheet l 6Z Y l Z.

IHHIHHII Ilhii, llHllllllllllll INVENTOR 14 175751? C. WEBL'R.

BY b f M ATTORNEY Sept. 23, 1937. w, WEBER R; 20,522

TUBE DRAWING Original Filed Dec. 18, 1930 3 Sheets-Sheet 2 INVENTOR BY um 75 c. M55512,

AM, 4- 62a ATTORNEY W. C. WEBER Sept. 28, 1937.

TUBE DRAWING Original Filed Dec. 18, 1930 I5 Sheets-Sheet 3 INVENTOR WIZTZKC. W58

M a ATTORNEY Reissued Sept. 28, 1937 PATENT OFFICE TUBE DRAWING Walter G. Weber, Corning,

N. Y., assignor, by

mesne assignments. to Corning Glass Works, Corning, N. Y., a corporation of New York Original No. 1,892,477, dated December 27, 1932,

Serial No. 503,293, December 18,

1930. Application for reissue November 30, 1934, Serial No.

22 Claims.

This invention relates to glass drawing, and

more particularly to the manufacture of glass tubing by flowing the molten glass over the crest of an annular curb projecting upwardly from the bottom of a container of molten glass, the interior of the curb forming a glass flowing orifice, at such head that the flowing glass does not fill the orifice but issues therefrom in a. hollow stream so formed means :are provided for chilling the inner surface of the stream by radiation from a cooling element while, if desired, means the exterior of the stream after it moves from oil the curb to fire-finish it. 'Ifh'e head of glass at the crest of the curb is preferably controlled by means of a vertically adjustable sleeve. dipping into the surface of the glass concentric with the curb. By the use of such a sleeve cold air-may stream and the cooling cooling effects.

A specific embodimentof my invention is set out in the following disclosure and shown in the accompanying drawings, in which:

- Fig. l is aside elevation of my apparatus;

Fig. 2 is aj plan view of my apparatus;

Fig. 3 is xa sectional view taken along the line 3-3 of F 2 Referring to the drawings in detail, a base I 0, rectangular in form and constructed preferably of channel girders is supported on depending journal members II in which wheels l2 are axled, the wheels providing movability for the apparatus. 5 Secured to the base are four angle irons I3 supporting a channeled casting I 4, which is formed with a large circular opening in its center surelement to accentuate the rounded b a flange l5 (Fig. 3). This casting is.

provided on its upper surface adjacent the fiange I5 with la ball race I6. A gear I! fits rotatably around the flange l5 and is provided with a ball race I3 which coacts with the ball race It and balls l9 to form an anti-friction bearing. A pinion (Fig. l) which is driven by any suitable power source, shown here as an electric motor 2| is journaled on the casting ll to engage gear I I. A housing 22 is positioned on the casting ll to enclose the gear I1, and sockets 23 are made'ini'tegral with the housing for a purpose which will behereinafter explained.

I Supported by lugs 24 (Fig. 3) on the gear I! and rotatable therewith is a casing 25 whose bottom is formed with a circular aperture 28 surrounded by an upstanding flange 21. A refrac-- tory bowl 23 rests on'the upper edge of the flange 21 and is separated from the. sides of the casing may be provided'for re-heating also be drawn down between the lnterior of the by insulating material 29, and formed in its bottom is an aperture 30 which registers with the aperture 26 in the casing. A ring 3|.is bolted to the bottom of the casing25 so that it'underlaps A the edge of the aperture 26 and supports a .re- 5 fractory cone 32 which extends upwardly into the interior of the bowl and snugly fits aperture 30. The upper end of the cone is formed with an inwardly extending annulus to form a circular glassdischarge orifice 33.

Secured to the under side of the casting ll are depending brackets 35 which support at their lower ends a fire-polishing and cooling unit positioned on the inside of the cone, concentric with the orifice 33. This unit consists of inner and outer cylinders 36 and 31 arranged in spaced concentric relation, the lower ends of these cylinders being connected by a base 38. The upper end of the inner cylinder 36 is flared outwardly while the upper end of the outer cylinder 31 is turned 20 inwardly at 33. Supported on the inturned portion 33 of the upper end of the outercylinder is a ring-shaped burner the orifices of which are designed to project a flame against the glass at the point where it emerges from the orifice 25 33 of the cone 32. Arranged in spaced concentric relation between the inner andouter cylinders 36 and 31 are cylinders ll and 42, the inner cylinder ll being oi. less height than the outer cylinder 42. Connected through the base 38 above re- 30 ferred to with the space between the innermost flared cylinder at and the shorter cylinder 4| is a pipe 43 for admitting cold water to the space between the cylinders. A water discharge pipe ll.

- is connected through the base 38 with the spacebetween the cylinders 4| and 42 and a flue leads from the space formed between the cylinder 42 and the outer-most cylinder 31 for drawing oil the products of combustion of theburner I0 40 by means of a suction fan (not shown). 7

A casting 46 is supported above the bowl by means of standards 41 the lower ends of which are inserted in the socket 23 of the housing 22. The casting is provided with an inwardly extend- 45 ing flange 49 supporting a refractory cover 50 which is in part dome-shaped with its lower edge extending over the upper edge of the bowl 28. Outstanding portions of the cover contain ports 5| through which suitable burners (not shown) 60 may be placed, and the sides of the cover extend parallel (Fig. 2) from the transverse center line of the apparatus and terminate in a perpendicular wall 52 which is located in a plane above the bowl 28 approximately midway between its cen- 55 ter and edge. This allows a portion of the bowl molten glass. The central portion of the cover is formed with an aperture 54 which is concentric with the cone 33.

Fitted in a socket at 56 in the casting and extending upwardly therefrom is a hollow standard 55 (Fig. 1) and vertically slidable on the standard is an arm 51 carrying a perforated lug 58 which is movable on a screw threaded member 59 upon which a nut 60 is adjustable to limit the downward movement of the arm 51. A cable BI is made fast to the arm 51 and runs over a pulley 62 and down the inside of the hollow standard 55 to a suitable Windlass and ratchet means, (not shown) which is operated by a hand wheel 63 (Fig. 2) to raise .the arm 51. Formed on the outer end of the arm 51 is a collar 64 to which a sleeve 65 is secured, and a claw piece 65 is clamped to the sleeve 65 for supporting a refractory sleeve 61 by engagement with its flanged upper edge. The sleeve 61, being supported by the arm 51, may be adjusted vertically by raising and lowering the arm and when lowered, by reason of the contact of the walls of the aperture in the lug 58 with the screw threaded member 59, the sleeve will be held in concentric relation to the orifice 33. An externally screw threaded pipe 68 fits movably in the supporting sleeve 65, the

threads on the pipe coacting with a threaded hand wheel 69 which is rotatably supported on the top of collar 64. This pipe carries at its lower end, and supplies water to, a cooler 10 which consists preferably of a cone-shaped water jacket. Extending into the jacket and concentric with the pipe 63 is a smaller pipe H which acts as an outlet for the water while concentric with this outlet pipe II and extending completely through the cooling means is an air-conducting tube 12 whose function will be hereinafter disclosed. The hand wheel 69 enables the cooler 10 to be raised or lowered to vary its distance from the glass flowing into the orifice 33. The water inlet pipe 38 is connected to a suitable water supply and the outlet pipe II is connected in any suitable manner with a discharge line for the waste water while the air conducting tube 12 is connected to any suitable air supply.

When the apparatus is to be operated, it is placed with the inlet 53 under the forehearth 13 of a furnace (not shown), the orifice 33 being posltioned directly over a hole It in the floor upon which the apparatus is supported. Located in the room below is a suitable tractor 15, such as is more fully disclosed in U. S. Patent No. 1,829,429.

In operation the bowl 28 is rotated at a constant rate of speed by the motor 2 I and a stream a: molten glass 'lfi regulated by a suitable gate 'l'l according to the size of the tubing to be drawn, flows into the bowl 23 from the forehearth 13. The glass flows under the edge of the sleeve 61, and as it rises inside of the sleeve, the cooler HI absorbs some of the heat which .is radiatedfrom the exposed surface 18 of the glass 16. The

molten glass in the bowl is kept at .such a height bore of the tubing, thereby producing a downthat its upper surface lies in a plane above the upper end of the cone 32 and hence the glass will fiow over the edge of the cone and through the orifice 33 which is large enough in diameter to keep the bore of the tube open, the plastic glass passing downwardly through the cone 32 and the cylinder 35. A steady fiow of air is maintained through the tube 12 to create a draft through the ward fiow of air between the cooler 10 and the surface of the glass at 18 which augments the I 20,522 to remain open at 33 to act as an inlet for the 36, it is directed through the hole I4 in the fioor to the tractor 15 by means of which it is drawn to size. This pulling operation may be accomplished by hand, or at times by gravity, but it has been found that a mechanical apparatus operating at a predetermined rate of speed will produce the best results.

The condition of the glass as it flows over the edge of the orifice 3| may, by varying the relation of the cooler 10 to the surface of the glass, be controlled so that a layer of glass having the correct plasticity for drawing is formed between the cone 32 and the lower edge of the sleeve 61. Since the layer of glass which is uppermost during the drawing operation eventually becomes the inside wall of the tube without contacting with any hard unyielding surface, it is not liable to injury or striation during the drawing operation and consequently the inside of the wall of the tubing will be free from imperfections. By means ,of the hand wheel 63 and the nut 60 the vertical position of the sleeve 61 may be so adjusted that the height of the glass in relation to the orifice 3| may be maintained and hence sufficient glass will flow over the edge'of this orifice to build up the I wall of the tube 19 to the desired thickness.

Owing to the initial temperature of the molten glass 16 and the cooling action of the cooler Ill, the temperature of the glass flowing over the edge of the orifice 33 increases with its depth or its distance from the cooled upper surface at, 18. Therefore, while the layer of glass which forms the inside surface of the'tube is sufficiently cooled to support the drawing operation, the glass which contacts the edge of the orifice and forms the outside of the tube may have sufficient fluidity to heal up any striations which may be formed thereon by slight irregularities of the orifice. The fiame from the burner 40 is directed so as to heat the orifice and also the surface of the glass as it leaves the orifice, thereby pleted by the absorption of the heat from thetube by the air below the bowl. Since the tubing is in a plastic state for a considerable distance below the bowl it may be drawn down to the required size by the tractor 15 before ithardens. The size of the finished product may be controlled by regulating the speed of the tractor or "by regulating the viscosity of the glass as it leaves the bowl or both. When the tubing is drawn rapidly, it will be drawn down to a small diameter before solidifying and a slower rate of draw will result in the production of tubing of larger diameter. Further, the viscosityof the glass as it leaves the bowl exercises an influence on the diameter of the tubing as an increased viscosity results in an increase of diameter.

When drawing tubing of large diameter, it may be found necessary to admit air under pressure to the inside of the tube whereupon a large amount of air may be forced through the air con-' ducting tube 12, but in the production of small tubing this is usually unnecessary. By experiglass in relation to the orifice 33, the condition of the glass at 18' and the speed of movement of the tractor 15, may be so adjusted in relation to each other as to rapidly produce perfect tubing of the desired dimensions. The bowl 28 may be rotated at a' constant rate of speed by the motor 2| to insure uniformity of the temperature and volume of the glass as it flows over the cone 32 and out of the orifice 33. Tubing of very precise dimensions throughout may' be produced in this manner, but when less exacting requirements are to be met, I have found-that good results may be obtained without rotating the bowl or even by utilizing a stationary container for the molten glass.

While the above disclosure sets out a specific embodiment of my invention, I consider that various changesjn structure may be made without violating the spirit of my invention and limit myself only to the scope of the appended claims.

It will be noted that the refractory cone 32 forms an annular curb arising from the bottom of the glass container or bowl 28 and surrounding a downwardly discharging orifice and that the molten glass contained in the latter flows over the crest of such curb into the orifice and in so flowing forms a hollow stream, the inner surface of which is exposed to the cooling radiation of the cooler 10. I the tube, as distinguished from the molten glass in the container, does not have its interior surface in contact with refractory material or a forming element of any kind but such wall or surface is due entirely to the natural flow of the glass over the crest of the curb. Hence the interior of the tube has a high finish while the exterior of the tube, which has been in contact-with the crest of the curb, is refinished by the burn- 1 What I claim is:- 1. In a glass tube making apparatus, a container for molten glass having an outlet orificefor the glass, means for coolinga portion of the glass in the container, and means surrounding the orifice for causing the molten glass which issues through it to assume the form of a hollow stream.

2.- In a glass tube drawing apparatus, a con tainer for molten glass having an outlet orifice, an upwardly projecting nipple in said orifice, a depending sleeve concentric with the nipple, cooling means in the sleeve, and means for drawing glass downwardly through the nipple.

3. In a glass tube making apparatus, a covered container for molten glass, a nipple projecting upwardly in the container, a sleeve extending through the cover into the container concentri cally with the nipple, means to cause a vdraftof air from outside the'container to flow over the surface of the glass inside the sleeve and coo-l a portion of the glass, and means to draw the cooled portion downwardly through the nipple.

4. In a tube drawing machine the combination with a container for molten glass having a hollow curb arising from the floor thereof and forming an outlet, of a sleeve,'whose lower diameter is substantially larger than the exterior diameter of the curb at its top, projecting into the glass from above, the sleeve being open to atmosphere, 2: member located in the curb and out of contact with the glass flowing therethrough, and means for introducing air into the interior of the tube formed by the curb below such member.

5. In an apparatus for the manufacture of 'I'husin the practice of my invention glass tubing, the combination with a container having a downwardly directed orifice formed by an annular curb in the bottom thereof, a cooled element located within the curb, and means forso regulating the rate of flow over the crest of the curb that the glass moves thereover from the container in an annular stream out of contact with the cooled element.

v6. In an apparatus for the manufacture of glass tubing, the combination of a container for molten glass having adownwardly directed orifice formed by an annular curb in the bottom thereof, and a vertically adjustable sleeve concentric with the orifice and projecting into the. glass from above and having a greater diameter than the crest of the curb.

7. In an apparatus for the manufacture of glass tubing, the combination of a container having a downwardly directed orifice formed by an annular curb in the bottom thereof, means for rotating the container around the axis of the orifice, and means for so regulating the head of 7 glass over the crest of the curb that the glass moves thereover and downwardly through the orifice in a hollow stream.

8. In an apparatus for the manufacture of glass tubing, the combination of a container having a downwardly directed orifice formed by an annular curb in the bottom thereof, means for rotating the container around the axis of the orifice, means for so regulating the head of glass over the crest of the curb that the glass moves thereover and downwardly through the orifice in a hollow stream, and a heater located below the orifice and acting on the exterior surface of the glass issuing therefrom.

9. Inan apparatus for the manufacture of glass tubing, the combination of a container having a downwardly directed orifice formed by'an annular curb in the bottom thereof, a cooled element 10- catedwithin the curb, and a vertically adjustable sleeve'concentric with the orifice and projecting into the glass from above and having a greater diameter than the crest of the curb, so regulating the rate of flow over the crest of the curb that the glass moves thereover from the container in a. hollow stream out of contact with the cooled element.

10. In an apparatus for the manufacture of glass tubing, the combination of a container having a downwardly directed orifice formed by an annular curb in the bottom thereof, a cooled element located within the curb, means for so regulating the rate of flow over the crest of the curb that the glass moves thereover from the container in a hollow stream, out of contact with the cooled element, and means for rotating the container around the axis of the orifice.

11. In an apparatus for the manufacture of glass tubing, the combination of a container having a downwardly directed orifice formed by an annular curb in the bottom thereof, a cooled element located within the curb, means for so regulating the rate of flow over the crest of the curb that the glass moves thereover from the container in a hollow stream out of contact with the cooled element, and a heater located below the orifice and acting on the exterior surface of the glass issuing therefrom,

12. In an apparatus for the manufacture of glass tubing, the combination of a container having a downwardly directed orifice formed by an annular curb in the bottom thereof, a vertically adjustable sleeve concentric with the orifice and projecting into the glass from. above and having and means for rotating the container around the axis of the orifice.

13. In an apparatus for the manufacture of.

adjustable sleeve concentric with the orifice andprojecting into the glass from above and having a greater diameter than the crest of the curb, and a heater located below the'orifice and acting on the exterior surface of the glass issuing therefrom.

14. In an apparatus for the manufacture of glass tubing, the comblnatlon'of a container having a downwardly directed orifice formed by an annular curb in the bottom thereof, a cooled element located within the curb, a vertically adjustable sleeve concentric with-the orifice and projecting into the glass from above and having a greater. diameter. than the crest of the curb for so regulating therate of fiow over the crest of the curb that the glass moves thereover from.-

the container in a-hollow stream out of contact with the cooled element, and means for rotating the container around the axis of the orifice.

15. In .an apparatus for the manufacture of glass tubing, the combination of a container having a downwardly directed orifice formed by an annular curb in the bottom thereof, a cooled element located within the curb, a vertically adjustable sleeve concentric with the orifice and projecting into the glass from above and havin a greater diameter'than the crest of the curb, for so regulating the rate of fiow over the crest of the curb that the glass moves thereover from the container in a hollow stream out of contact with the cooled element, and means for introducing air under pressure into the tube below the cooling member.

16. The hereinbefore described method of making glass tubing which comprises flowing glass from a reservoir of molten glass over the crest of an annular curb in a hollow stream, the interior surface of the annular stream being free of contact with a former and chilling such interior surface by radiation.

17. The hereinbefore described method of ma!- a greater diameter than the crest of the curb;

ing glass tubing which comprises flowing glass from a reservoir of molten glass over the crest of an annular curb in a hollow stream, the interior surface of the stream being free of contact with a former and chilling such interior surface by radiation, and by currents of cold air.

18. The hereinbefore described method of making glass tubing which comprises flowing glass from a reservoir of molten glass over the crest of an annular curb, so limiting the rate of flow that the orifice formed by the annular curb is not filled by the flowing glass, and chilling the interior surface of the hollow glass at the curb by radiation from a chilled member located within the curb.

19. The hereinbefore described method of making glass tubing which comprises .fiowing glass from a reservoir of molten glass over the crest of an annular curb, limiting the rate of flow over such curb so that the orifice is not filled with flowing glass, and controlling the thickness of the tube so formed by determining the fiow over the crest of the curb.;

20. In a tube making apparatus; a chamber adapted to receive molten glass, said chamber having a peripherally unobstructed overflow orifice formed therein lying in a substantially horizontal plane above the level of the bottom of the chamber, a glass furnace adapted to-suppl-y glass to said chamber, a conduit extending between said furnace and "said chamber, and means for controlling the'rate of fiow of glass through said conduit. l

21. Apparatus for forming glass tubes comprising a chamber for holding molten glass, said rate of cular overflow opening therein above the bottom thereof lying in a horizontal plane,,means for supplying glass to said chamber to overflow the edges of said opening, and means for admittin air above said orifices. I

22. The method of forming glass tubes which consists in-causing molten glass from the upper surface of a bath to fiow in a thin sheet over the edge of a circular orifice within the bath having a vertical axis and admitting air above said orifice.

WALTER C. WEBER.

chamber having a peripherally unobstructed cir- 

